The invention relates to a process and a device for filling cavities, and particularly mold cavities, with a reactive, flowable mixture which forms into foam or a solid material, where at least two reaction components are introduced into a mixing zone, where they are mixed and are subsequently introduced into the cavity.
It is the purpose of the invention to fill cavities such as car body parts, with solid materials (and preferably foam materials) and to produce parts in molds by placing a reaction mixture into the mold cavity. Extremely useful molded parts may be produced from polyurethane materials. In general, the reactive components to produce such materials are introduced into the cavity or mold and allowed to react therein. Because increasingly faster reacting mixtures are used in the art in order to decrease the demolding time, and since increasingly larger cavities must be filled to produce larger parts, it is difficult to introduce the entire reaction mixture into the cavity before the reaction starts. The art is aware that the feed of the reaction mixture should utilize a flow front that avoids air enclosure. According to U.S. Pat. No. 3,991,147, it was attempted to obtain such a flow front by following exactly defined conditions. This method will generally fail, however, when large volumes and high reaction speeds no longer allow the observance of those defined conditions.
Another measure used in the art is to provide a sufficiently long gate channel, which calms down the flow. This, however, results in a high material loss. Additionally, the molded part is generally marked by an unsightly gate mark.
Thus, the problem to be solved is to find a process and a device which make it possible to introduce highly reactive mixtures and/or large volumes of mixtures into a cavity, while avoiding the enclosure of air, so that perfect fillings or molded parts are obtained.